Renal transplant patients are at high risk of hyperparathyroidism, largely because of long-lasting renal insufficiency before transplant, and of progressive deterioration of kidney function because of chronic allograft nephropathy (a disease of proteinuria and progressive decline of the glomerular filtration rate).In hemodialysis patients, intravenous paricalcitol (19-nor-1,25-dihydroxyvitamin D2), a new vitamin D analogue, achieves a faster and more effective normalization of parathyroid hormone (PTH) levels than calcitriol (1,25-dihydroxyvitamin D3), an effect that is associated with smaller changes in serum calcium and phosphorus levels.